KOBUNSHI RONBUNSHU
Online ISSN : 1881-5685
Print ISSN : 0386-2186
ISSN-L : 0386-2186
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Volume 64, Issue 5
Displaying 1-8 of 8 articles from this issue
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Comprehensive Papers
  • Two-dimensional Molecular Aggregation Structure and Thermal Molecular Motion of Polyalkylsiloxane Ultrathin Films
    Tomoyuki KOGA, Koji HONDA, Sono SASAKI, Osami SAKATA, Atsushi TAKAHARA
    2007 Volume 64 Issue 5 Pages 269-279
    Published: 2007
    Released on J-STAGE: October 01, 2007
    DOIhttps://doi.org/10.1295/koron.64.269
    JOURNAL FREE ACCESS
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    Two-dimensional molecular aggregation states of polyalkylsiloxane ultrathin films on silicon wafer substrates surface were investigated by various techniques. The in-plane grazing incidence X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and scanning force microscopy revealed that the alkyl chains in the octadecyltrimethoxysilane (OTMS) ultrathin films prepared by the CVA method (OTMS-CVA) are in an amorphous state at room temperature. On the other hand, octadecyltrichlorosilane (OTS) ultrathin films prepared by the solution chemisorption method and water-cast method are in a hexagonal crystalline state. According to lateral force microscopic measurements, the transition temperature from the hexagonal crystalline phase to the amorphous phase was found to be ca 333 K for the OTS ultrathin film prepared by the chemisorption method. However, the phase transition was not clearly observed in the OTMS-CVA ultrathin film. These results indicated that organosilane compounds in the ultrathin film prepared by the CVA method were immobilized on the silicon wafer substrate surface in an amorphous state, which was quite different from the hexagonal crystalline state obtained by the solution chemisorption and water-cast methods.
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Original Papers
  • Simulation of the Inclusion Complex Formation between Cyclodextrin and Polymer Chain
    Naohito URAKAMI, Junko IMADA, Chihiro FUJIOKA, Takashi YAMAMOTO
    2007 Volume 64 Issue 5 Pages 280-285
    Published: 2007
    Released on J-STAGE: October 01, 2007
    DOIhttps://doi.org/10.1295/koron.64.280
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    The inclusion complex formation process between cyclodextrin (CD) and a polymer chain was investigated using a molecular dynamics method. In particular, the mechanism of formation of a pseudorotaxane and a pseudopolyrotaxane, and the ordered structure formation between pseudopolyrotaxanes were studied. In these simulations, the ring and chain were used as a coarse-grained model of CD and a polymer chain. The simulation results of pseudorotaxane formation showed that an inclusion complex is formed due to the non-bonded interaction between ring and chain. In formation of the pseudopolyrotaxane, the structure of chain transforms from the random coil to the elongated state, as the number of rings included in the inclusion complex is increased. The simulation results indicated that a few rings and a chain repeated the process of inclusion and dissociation after formation of a pseudopolyrotaxane with several rings. Furthermore, the formation of the orientational ordered structure between pseudopolyrotaxanes was also observed in these simulations.
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  • Molecular Mobility of Chain Ends of Matrix Chains in Phase-Separated Di-block Copolymers
    Katsuhiro YAMAMOTO, Kota NANBU, Yohei MIWA, Hideaki TAKAGI, Shigeo HAR ...
    2007 Volume 64 Issue 5 Pages 286-293
    Published: 2007
    Released on J-STAGE: October 01, 2007
    DOIhttps://doi.org/10.1295/koron.64.286
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    Molecular motion of end segments of polystyrene chains in polystyrene(PS)-b-poly(methyl acrylate) (PMA) forming phase-separated structures of spherical, cylindrical, and lamellar morphology was investigated by ESR spin-label method. The PMA volume fraction was kept below 55% to have PS block constitute a matrix component. Phase-separated structures of PS-b-PMA were confirmed by SAXS. No phase-transition was observed in the temperature range employed in the present study. In bulk PS, the free volume around the chain end is relatively large, and the segmental mobility around chain ends is generally high. In the block copolymer, the molecular mobility around PS end segments was also found to be higher than that around inner PS segments. Moreover, the difference in transition temperature between the end and inner segments was larger than that in bulk PS. These results are considered to be related to the conformation of PS chains in the phase-separated structures. Chain ends in a microdomain have been theoretically and experimentally shown to be populated more around the center of the microdomain. This effect of chain end segregation activates molecular motion around the PS end segments. The segregation effect depends on the morphology and influences the mobility around the chain ends.
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  • Phase Separation Kinetics and Morphology of Light-Induced IPN Confined in Micrometer Scales
    Atsushi MASUNAGA, Soh ISHINO, Hideyuki NAKANISHI, Qui Tran-Cong-MIYATA
    2007 Volume 64 Issue 5 Pages 294-300
    Published: 2007
    Released on J-STAGE: October 01, 2007
    DOIhttps://doi.org/10.1295/koron.64.294
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    The reaction and phase separation kinetics of interpenetrating polymer networks (IPNs), prepared by photopolymerization of methyl methacrylate (MMA) and photo-crosslinking of polystyrene (PS), were examined in situ by using Fourier-transform infrared (FT-IR) spectroscopy and phase-contrast and laser-scanning confocal microscopy. Photopolymerization of MMA exhibited an autocatalytic behavior and the reaction yield increased with increasing light intensity. The phase separation process on the other hand, was suppressed by the reaction occurring at the later stage of irradiation, resulting in co-continuous morphology with variable characteristic lengths. By localizing the domains undergoing phase separation by irradiation with a single strip of light, whose width varied from 500 to 60 μm, it was found that the characteristic length of the spinodal structures depends on the scale of spatial confinement. These results were discussed in terms of phase separation under thermodynamically open conditions.
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  • Structural Characterization of Crosslinking Points of Natural Rubber (E-Configuration) by Latex, Solution and Solid State 13C NMR Spectroscopy
    Jinta UKAWA, Yoshimasa YAMAMOTO, Seiichi KAWAHARA
    2007 Volume 64 Issue 5 Pages 301-308
    Published: 2007
    Released on J-STAGE: October 01, 2007
    DOIhttps://doi.org/10.1295/koron.64.301
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    Structural characterizations of crosslinking points of vulcanized natural rubber were carried out by latex, solution and solid state 13C NMR spectroscopy. 13C NMR signals, newly appearing after vulcanization of natural rubber, were assigned to the crosslinking points by latex state 13C NMR spectroscopy with DEPT and APT pulse sequences. The crosslinking points were suggested to be trans-units formed after isomerization by comparison with 13C NMR spectra for vulcanized natural rubber and trans-1,4-polyisoprene. The stereo structure of crosslinking points of vulcanized natural rubber was proved by DEPT, APT and 2-dimensional NMR spectroscopy for vulcanized squalene as a model.
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  • Transient Network Structure of ABA Triblock Copolymer Solution and Its Deformation and Reconstruction Behavior
    Katsuhiro INOMATA, Ai BANNO, Eijiro SATO, Hideki SUGIMOTO, Eiji NAKANI ...
    2007 Volume 64 Issue 5 Pages 309-316
    Published: 2007
    Released on J-STAGE: October 01, 2007
    DOIhttps://doi.org/10.1295/koron.64.309
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    Transient network structures of ABA triblock copolymer, poly(methyl methacrylate)-block-poly(tert-butyl acrylate)-block-poly(methyl methacrylate) (PMMA-PtBuA-PMMA) in a solvent selective for the middle block have been investigated by means of small-angle X-ray scattering (SAXS) and viscoelastic measurements. In the SAXS profiles for solutions just above a sol-gel transition concentration, no correlation peaks corresponding to distances between PMMA cores bridged by PtBuA chain were observed, suggesting that significant amounts of PMMA associated cores are not included in the transient network. Even after step shear flow performed on 8.0 wt% solution in physical gel state, the linear dynamic viscoelasticity was almost identical with the result obtained before the shear flow. On the other hand, the step shear flow for 4.4 wt% solution reduced the plateau storage modulus by almost half. These linear and nonlinear viscoelasticities revealed that the deformation and reconstruction behavior of the transient network by the shear flow is influenced by the denseness of the network structure as well as by the association strength of the PMMA core.
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  • Microdomain Orientation in Chelate-Doped Block Copolymers by A High Magnetic Field
    Akifumi YASUI, Fumiko KIMURA, Tsukasa KIYOSHI, Tsunehisa KIMURA, Jeong ...
    2007 Volume 64 Issue 5 Pages 317-323
    Published: 2007
    Released on J-STAGE: October 01, 2007
    DOIhttps://doi.org/10.1295/koron.64.317
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    Magnetic orientation of microdomain structures has been examined for block copolymers consisting of non-crystalline block chains. In order to enhance the effect of the magnetic field, the difference in magnetic susceptibility between the microdomain (dispersed phase) and the matrix phase was increased by doping a metal chelate selectively in the microdomain. A polystyrene-block-poly(ethylene-co-but-1-ene)-block-polystyrene triblock copolymer (SEBS), which forms polystyrene (PS) cylinders in the poly(ethylene-co-but-1-ene) (PEB) matrix, was employed. By solution casting using dichloromethane, a good solvent selectively for PS, non-equilibrium lamellar microdomains were formed and frozen in the as-cast film. The SEBS sample, cast on aluminum foil in the presence of a high magnetic field of 12 T, was then annealed at 190°C for 3 h. The orientation of PS cylinders was examined by small angle X-ray scattering at room temperature. It was found that the lamellar microdomains were oriented parallel to the magnetic field. After annealing, 6-folded pattern appeared, which was ascribed to well-ordered cylinders aligned parallel to the applied magnetic field.
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  • Computer Simulation Study on the Shear-Induced Phase Separation in Semi-Dilute Polymer Solutions by Using Ianniruberto-Marrucci Model
    Shotaro NISHITSUJI, Mikihito TAKENAKA, Takashi TANIGUCHI, Hirokazu HAS ...
    2007 Volume 64 Issue 5 Pages 324-327
    Published: 2007
    Released on J-STAGE: October 01, 2007
    DOIhttps://doi.org/10.1295/koron.64.324
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    We developed a new computer simulation scheme with Doi-Onuki theory, where the Ianniruberto-Marrucci model is employed as the constitutive equation, to simulate the dynamics of the shear-induced concentration fluctuations and/or phase separation in semi-dilute polymer solutions. The scheme can well simulate not only the time-evolution of shear-induced structure but the overshoot behavior in shear stress which is experimentally observed in semi-dilute polymer solutions.
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